/*
这个方法是获取嵌套层数
 */
Array.prototype.getLevel = function () {
    let max = 1
    for (const a of this) {
        if (a instanceof Array) {
            const depth = a.getLevel() + 1
            if (max < depth) max = depth
        }
    }
    return max
};
const a1 = [1, 2, [1], [1, [2, [3]]]];
console.log(a1.getLevel()); //4
